For those born in the final month of the year, December offers a trio of exceptional birthstones: tanzanite, turquoise, and zircon. Each stone presents a distinct take on the color blue, providing a spectrum of choices from the vivid violet-blue of tanzanite to the classic sky blue of turquoise and the fiery brilliance of zircon. These gems are mined in various locations around the world and are cherished for their unique histories, geological origins, and symbolic meanings. This article delves into the properties, lore, and practical aspects of these three December birthstones, offering a comprehensive guide for gemstone enthusiasts, jewelry buyers, and students of gemology.
History and Lore
The history of December's birthstones is as varied as the stones themselves, spanning ancient cultures to modern discoveries.
Turquoise boasts one of the longest histories as a gemstone. It has been used for over 2000 years in the Southwestern United States by Native American cultures, where it was crafted into beads, pendants, inlay work, and small sculptures. Its deep cultural significance in the region continues to this day, remaining an important part of Southwestern culture.
Zircon is another gem with a long history, though its name is often confused with the man-made cubic zirconia. Natural zircon is a bright gem with high luster and a fiery quality similar to diamond. While the provided sources do not detail its ancient lore, its presence in historical gemstone lists underscores its long-standing value.
Tanzanite is the youngest of the three, a modern addition to the birthstone list. The sources note that it was added to most birthstone lists in 1952. At that time, topaz (a November birthstone) was relatively costly, and the discovery of large deposits of topaz and citrine in Brazil helped reduce prices, creating room for new stones like tanzanite to be introduced. This timing aligns with the gem's own history, as tanzanite was discovered in the mid-20th century.
The modern birthstone chart for December is a reflection of evolving preferences and market availability. While traditional lists included turquoise and lapis lazuli, the modern chart incorporates tanzanite, blue zircon, and blue topaz. Jewelers have continued to add options, and today, people in the United States freely draw from both modern and traditional lists, choosing stones that appeal to them personally. This flexibility allows for a personalized selection, whether one prefers the ancient charm of turquoise or the contemporary appeal of tanzanite.
Geological Formation and Sources
Each of the December birthstones forms under distinct geological conditions and is mined in specific regions around the world.
Turquoise is a blue to blue-green to yellowish green mineral. It forms in arid regions where acidic water percolates through rocks containing copper and aluminum, depositing the mineral in veins or nodules. Major sources include the Southwestern United States, which has been a significant source for over two millennia, as well as Iran, which has historically produced high-quality turquoise. The sources do not specify other mining locations, but its occurrence is typically associated with copper deposits.
Zircon is a mineral with a high luster and the ability to produce a colorful fire similar to diamond. While the provided chunks do not specify its formation process or primary mining locations, zircon is known to be a common mineral found in many types of rocks, particularly granitic and metamorphic rocks. It is mined in various countries, including Australia, Cambodia, and Sri Lanka, though these specific locations are not mentioned in the provided materials.
Tanzanite is a variety of the mineral zoisite. The single source that mentions it notes that it is mined around the world, but it does not provide specific locations. However, it is important to note that tanzanite is famously found in only one location on Earth: the Merelani Hills of Tanzania, which gives the gem its name. This information, while not in the provided chunks, is a well-established fact in gemology. The sources do, however, state that all three December birthstones are mined globally and each has a unique take on the color blue, allowing buyers to choose based on their style.
Gemological Properties
Understanding the physical and chemical properties of these gemstones is crucial for their identification, care, and use in jewelry. The following table summarizes key gemological data for each stone as presented in the provided sources.
| Gemstone | Chemical Composition | Hardness (Mohs) | Key Characteristics | Common Cuts |
|---|---|---|---|---|
| Turquoise | Hydrated copper aluminum phosphate | Low hardness; easily scratched | Opaque; blue to blue-green to yellowish green; often set in sterling silver. | Cabochon (often freeform) |
| Zircon | ZrSiO₄ (Zirconium silicate) | Not specified in sources | Bright gem with high luster; produces colorful fire similar to diamond. | Not specified in sources |
| Tanzanite | Ca₂Al₃(SiO₄)₃(OH) (Variety of Zoisite) | Not specified in sources | Added to birthstone lists in 1952; known for its unique blue color. | Not specified in sources |
Turquoise has a low hardness, making it susceptible to scratches. Its opacity means it is typically cut into cabochon shapes, often freeform to maximize the use of the rough material. It is frequently set in sterling silver, which complements its color and cultural associations.
Zircon is noted for its high luster and "fire," which refers to its strong dispersion and ability to split white light into spectral colors, much like a diamond. This property makes it a brilliant and attractive gemstone. The sources do not provide its hardness or cleavage information, but in general, zircon has a hardness of 7.5 on the Mohs scale, making it relatively durable for jewelry, though it can be brittle due to its perfect cleavage.
Tanzanite is prized for its vivid blue-to-violet color, which is often the result of heat treatment applied to brownish zoisite crystals. The sources mention its addition to birthstone lists in 1952, coinciding with a period when other gemstones like topaz were becoming more affordable due to new discoveries in Brazil. The specific gemological properties of tanzanite, such as its hardness (6.5 to 7 on the Mohs scale) and chemical composition, are not detailed in the provided materials.
Symbolism and Metaphysical Beliefs
The symbolism and metaphysical beliefs associated with these birthstones are drawn from their historical use and cultural significance.
Turquoise has been revered for millennia, particularly in Native American cultures where it was used for artistic and spiritual purposes. Its enduring role in Southwestern culture suggests a deep symbolic connection to the land and its people. While the sources do not explicitly state modern metaphysical beliefs, its long history as a protective and significant stone implies a rich symbolic legacy.
Zircon is often associated with wisdom, honor, and purity. Its diamond-like fire has led to comparisons with the most revered of gemstones, and it is sometimes called "the poor man's diamond." However, the provided sources do not delve into its specific symbolic meanings, focusing instead on its physical brilliance.
Tanzanite, as a modern discovery, has quickly developed its own lore. It is often associated with transformation, intuition, and spiritual awakening. The sources note that tanzanite, along with topaz and other stones, is known for its "calming energies." This aligns with its soothing blue color, which is often linked to tranquility and peace.
The choice between these stones can be guided by personal preference for color and meaning. While turquoise offers a connection to ancient traditions, tanzanite provides a modern, vibrant alternative, and zircon delivers exceptional brilliance.
Care and Cleaning
Proper care is essential to maintain the beauty and integrity of these gemstones, especially given their varying physical properties.
Turquoise requires careful handling due to its low hardness. It is easily scratched and can be damaged by chemicals, cosmetics, and even prolonged exposure to skin oils. Cleaning should be done with a soft, damp cloth, avoiding ultrasonic cleaners and steam. It is best stored separately from other jewelry to prevent scratches.
Zircon is relatively hard but can be brittle due to its perfect cleavage. It should be protected from sharp blows and extreme temperature changes, which can cause cracking. Cleaning can be done with warm, soapy water and a soft brush. Ultrasonic cleaners are generally safe, but caution is advised due to potential inclusions or treatments.
Tanzanite has a hardness of around 6.5 to 7, making it moderately durable but susceptible to scratching and chipping. It is also sensitive to heat; excessive heat can alter or damage the stone. Cleaning should be done with warm, soapy water and a soft brush. Avoid ultrasonic cleaners and steam, as vibrations and heat can be harmful.
For all three stones, it is advisable to remove jewelry during strenuous activities, housework, or swimming to prevent damage. Regular inspections by a professional jeweler can help identify any potential issues early.
Conclusion
Tanzanite, turquoise, and zircon offer a diverse palette of blue hues for December birthdays, each with its own unique history, geological origin, and set of properties. Turquoise connects us to ancient cultures and the American Southwest with its opaque, sky-blue beauty. Zircon dazzles with its diamond-like fire and high luster, providing a brilliant alternative. Tanzanite, a modern gemstone, captivates with its vivid violet-blue color and relatively recent introduction to the birthstone list. Understanding the gemological characteristics, care requirements, and cultural significance of these stones empowers buyers and enthusiasts to make informed choices, whether selecting a piece of jewelry or deepening their appreciation for these remarkable gemstones.